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This disclosure presents an independent vane type rotary machine for pressurization of gaseous and vaporous fluids at measures of pressure amplification and throughput commonly related to industrial scale fluid pressurization service. For the purposes of this disclosure xe2x80x9cindustrial scale fluid pressurization servicexe2x80x9d is defined as gas/vapor manipulation involving a pressure amplification ratio in excess of five and input power in excess of two kilowatts.
At the present time compressors used for industrial scale compression of gaseous or vaporous fluids are either reciprocating piston machines or multiple stage turbo machines. Reciprocating piston compressors amplify fluid pressure through direct mechanical manipulation of volume by means of reciprocating motion of a piston within a closed cylinder. Mechanically actuated valves control induction and discharge of throughput fluid. Reciprocating piston compressors offer good measures of efficiency and operational flexibility but reciprocating motion of dynamically significant components creates an inherent source of undesirable mechanical noise and vibration. Turbo type compressors accomplish pressure amplification through dynamic interaction of throughput fluid with purely rotational mechanical components and function without mechanically activated throughput induction and discharge valves. In comparison with reciprocating piston compressors, turbo type compressors are substantially free from mechanical noise and vibration but offer economic superiority only in applications requiring relatively large measures of continuously sustained input power.
Over a number of years significant inventive effort has been directed toward the derivation of a rotary type fluid manipulation machine offering operational flexibility as given by reciprocating machines but without incurring the use of reciprocating components. Radial vane type rotary machines have been the focus of particular attention in this regard. Radial vane rotary compressors ideally feature pressure amplification by volume manipulation without the use of reciprocating mechanical components and potentially offer good measures of power density, functional efficiency, and mechanical reliability. Radial vane rotary machines have been commonly developed to function as relatively small fluid pumps and small fluid driven motors but, as of the time of this disclosure, no radial vane type rotary machine is known to function as a gas/vapor compressor with industrial scale measures of pressure amplification and throughput.
In general, radial vane rotary machines primarily consist of a stationary containment structure and an internal rotational assembly. The stationary containment structure primarily consists of a containment cylinder installed with a mechanically secured closure structure at each axial end and with ports for induction and discharge of throughput fluid. Although particular design features may vary, the internal rotational assembly essentially consists of a rotational shaft, a rotational armature, and a plurality of radially oriented vanes. The rotational shaft extends through and is radially constrained by rotational bearings in one or both end closure structures and mechanically interfaces with an external power source. The rotational shaft is aligned with its rotational axis parallel to the axis of the containment cylinder bore. The rotational armature is concentrically secured on the rotational shaft and is diametrically proportioned to create an annular void between its periphery and the containment cylinder bore. The radially oriented vanes are individually installed and radially slide within radial vane slots equidistantly spaced around the periphery of the rotational armature. Each radially oriented vane axially extends through the axial length of the rotational armature and radially extends from within the radial vane slot to contact, or closely approach, the containment cylinder bore. The radial vanes collectively subdivide the aforesaid annular void into a plurality of segmental cells. Each axial end of each segmental cell is closed by and axial end closure ring or the inside surface of an end closure structure. Through geometric separation of the axis of the rotational armature from the axis of the containment cylinder bore, or through shaping of the containment cylinder bore, the relative volume of each segmental cell is dependent upon the rotational position of the rotational armature. Rotation of the rotational armature causes cyclical manipulation of segmental cell volume in a manner functionally analogous to the volume manipulation accomplished by piston movement in a reciprocating piston machine. For given proportions of containment cylinder bore, the magnitude of manipulated volume is inversely influenced by the diameter of the rotational armature and the plurality and thickness of the radial vanes. The extent of volume manipulation is directly influenced by the plurality of radial vanes, the magnitude of radial separation of the axes of the rotational shaft and the containment cylinder bore axis and/or by the shaping of the containment cylinder bore. The extent of volume manipulation may also be influenced by the sector width and sector location of ports allocated for induction and discharge of throughput fluid.
Rotary vane machines may feature either xe2x80x9ctrans-axial bladexe2x80x9d or xe2x80x9cindependent vanexe2x80x9d type radial vane arrangements. In the trans-axial blade type vane arrangement each radial vane slot extends through the axial length and diameter of the rotational armature. Each radial vane slot accommodates a sliding blade proportioned to closely approach the diameter of the containment cylinder bore and thus create two radial vanes. As trans-axial blades intersect the rotational armature axis a plurality of radial vanes in excess of two requires interlacing of the trans-axial blades. Interlacing impairs the radial strength of the trans-axial blades and thereby imposes a constraint on radial vane plurality. Interlacing of four trans-axial blades to provide eight radial vanes is about the practical in limit obtainable within the constraints of commonly available materials and acceptable rotational speeds. Analysis demonstrates that rotary vane machines with eight radial vanes do not provide the measure of single-stage pressure amplification appropriate for industrial-scale gas/vapor compressor service. Single-stage pressure amplification may be enhanced by incorporation of mechanically actuated fluid control valves but such measure necessarily incurs increased mechanical complexity and reduced functional efficiency. For these reasons trans-axial blade type rotary vane machines are precluded from further discussion.
In the independent vane arrangement each radial vane functions as an independent entity and so this arrangement precludes the requirement for blade interlacing and its constraint on blade plurality. Because of this feature independent vane type rotary vane machines offer an approach to achieving relatively high measures of single-stage pressure amplification without mechanically actuated throughput control valves. Independent vane type rotary machines have been substantially addressed in prior art and technology presented in prior art may be deemed adequate for engineering of liquid pumps and relatively small gaseous fluid manipulation devices. However physical laws related to similitude, mechanical fiction and adiabatic compression render much of the technology addressed in prior art inapplicable for engineering of gaseous fluid compression machines intended to provide industrial scale service. The influences of physical laws on the principal functional requirements of rotary vane machine technology as presented in prior art are briefly reviewed in the following paragraphs.
As previously noted independent vane type rotary machine require each radial vane to be individually radially constrained to resist centripetal force induced by rotation of the armature. In U.S. Pat. No. 3,447,477, U.S. Pat. No. 3, 973,881, and U.S. Pat. No. 4,772,190 radial constraint of radial vanes is accomplished by simply allowing the radial vanes to make sliding contact with the containment cylinder bore. In U.S. Pat. No. 985,091 radial vanes are collectively constrained by a pair of rotating rings partially embedded in the bore of the containment cylinder and in U.S. Pat. No. 2,590,132 radial vanes are individually constrained by engagement of a cylindrical axial protrusion with an axially constrained but freely rotating component installed at each end. Later disclosures present approaches for radially constraining radial vanes by means of roller and cam devices. U.S. Pat. No. 5,087,183 and U.S. Pat. No. 5,452,998 each feature an approach in which each radial vane is fitted with an axially aligned cylindrical protrusion and tether component installed close to its radially innermost axial edge at each axial end which is radially constrained by a rotational bearing embedded in the adjacent end enclosure structure. All radial constraint concepts noted above incur comparatively large measures of relative motion at interfacing load-bearing surfaces and, hence, substantial dissipation of input energy through mechanical friction. For geometrically similar machines the fraction of input energy dissipated by mechanical friction proportionally increases as a function of scale, rotational velocity and pressure amplification. In view of these considerations the technical approaches to radial vane constraint presented in the prior art noted above although functionally viable for small pumps and small gaseous fluid compression machines are deemed to incur such measures of mechanical friction as to be functionally non-viable for geometrically similar machines featuring the physical characteristics appropriate for industrial service. U.S. Pat. No. 2,414,187, U.S. Pat. No. 3,360,192, U.S. Pat. No. 6,024,549, and Japan Patent No. 63-9685 all feature an approach in which the radial vanes are collectively constrained by an axially extended flange on the periphery of a freely rotating disk or ring component at each axial end. In comparison with other prior art the technique of radial vane constraint presented in these latter disclosures significantly reduces the linear extent of relative motion at interfacing load-bearing surfaces and consequentially diminishes the fraction of input energy dissipated by mechanical friction.
Independent vane type rotary machines require each radial vane to incur reciprocating sliding motion relative to the rotational armature and, hence, dissipation of input energy through frictional interaction at the dynamic interface. As both sides of the radial vane must be constrained the consequence of thermal expansion in the thickness of the radial vane is a viability consideration. Additionally the reciprocating motion of the radial vane within the radial vane slot requires the base of each radial vane slot to be adequately vented in order to preclude radial vane seizure through hydraulic lock. The approach to radial constraint of radial vanes presented in prior art simply features sliding contact between the sides of the radial vane and the sides of the radial vane slot and prior art is silent regarding accommodation of thermal expansion and need for minimizing energy dissipation due to friction at the sliding surfaces. Also approaches to radial vane installation presented in prior art ignore the specific requirement for radial vane slot venting or imply that hydraulic lock at the radial vane base is precluded by ancillary pumping through lubrication ports in the rotating armature. U.S. Pat. No. 6,024,549 features a rotating armature configured as a hollow structural annulus and radial vane slots that penetrate the full thickness of the annulus wall. The approach to radial vane constraint as presented in this latter disclosure thus precludes energy dissipation through radial vane slot base pumping however the disclosure is silent regarding thermal expansion and friction reduction considerations. For geometrically similar machines the extent of thermal expansion is proportionally related to scale and component temperature. The fraction of input energy dissipated by frictional interaction and ancillary pumping within the radial vane slot are proportionally related to scale, pressure amplification, and rotational velocity. Because of such scaling relationships the functional characteristics of the means of radial vane constraint become increasingly significant from a functional viability viewpoint as machines increase in size. For these reasons the approaches to radial vane constraint as presented in prior art although adequate for small-scale fluid movement machines are deemed inadequate for rotary vane fluid compression machines featuring the physical characteristics appropriate for industrial service.
Radial vane rotary machines require the segmental cells to be effectively closed at each axial end. U.S. Pat. No. 5,087,183 and U.S. Pat. No. 5,452,998 feature closure of the axial ends of segmental cells by closely fitting the axial interfaces between rotational components and end closure structures. U.S. Pat. No. 985,091 features installation of a non-rotating sealing disk at one axial end of the rotational armature which may be axially adjusted to minimize or eliminate the distance of separation at the axial interfaces between rotational components and stationary structures. U.S. Pat. No. 2,414,187, U.S. Pat. No. 3,360,192, and Japan Pat. No. 63-9685 each feature installation of an axially constrained but freely rotating sealing ring at each axial end of the rotational armature. U.S. Pat. No. 2,590,132 features an approach by which each radial vane slot is axially closed by an axially constrained but freely rotating disk installed at one axial end of the rotational armature and an axially constrained but freely rotating ring at the other. None of the approaches noted above provide the axial resiliency to accommodate axial thermal expansion of rotational components and are therefore deemed non-viable for industrial scale gas compression machines in which significant frictional and adiabatic heating and consequential thermal expansion may be expected. U.S. Pat. No. 3,447,477, U.S. Pat. No. 3,973,881, and U.S. Pat. No. 4,772,190 each feature an approach in which the axial ends of radial vane slots are closed by axially constraining the rotating armature and the radial vanes between a non-rotating wear plate at one axial end and a non-rotating axially resilient cheek-plate at the other. Axial resiliency of the cheek plate is maintained by an axial compression spring and pressurized throughput fluid. In this case axial resiliency of the cheek plate precludes thermal expansion concerns but the non-rotational mobility of the axially constraining components entails significant energy dissipation through a substantial measure of relative motion at their frictional interfaces with rotational components. As the fraction of input energy dissipated by frictional interaction at the axial interface is proportionally related to scale, rotational velocity, and pressure amplification it is believed that the application of this approach in industrial-scale gas compression machines would incur such energy dissipation as to be unacceptable from a mechanical efficiency viewpoint. U.S. Pat. No. 6,024,549 features installation of axially and rotationally mobile axial end closure components. The approach to axial closure presented in this disclosure provides the means to resiliently accommodate thermally induced dimensional adjustments in associated components and precludes significant energy dissipation through mechanical friction and in view of these attributes is considered to be appropriate for application in industrial-scale gas compression machines.
Machines compressing gaseous fluids are subject to component heating caused by both adiabatic effects of throughput fluid compression and friction at mechanically dynamic interfaces. The functional viability of a machine is dependent upon component temperatures being within thresholds prescribed by lubrication and/or structural constraints. The measure of heat energy produced by a gaseous fluid compression machine is directly related to its functional capability in terms of pressure amplification and throughput. For this reason commonly available industrial scale gaseous fluid compressors incorporate means of thermal control for both external and internal components and it is anticipated that similar thermal control is necessary for rotary vane gaseous fluid compression machines intended to demonstrate comparable performance capabilities. Rotary vane machine concepts presented in prior disclosures often address means of thermal control for stationary containment structures but substantially disregard thermal control for internal dynamic components and, hence, ignore a requirement essential for the functional viability of industrial-scale machines.
In summary it is concluded that the rotary vane machine technologies presented in prior art although possibly adequate for rotary vane type gaseous fluid compression machines featuring small measures of physical size, pressure amplification, and throughput but inadequately address several mechanical issues which, through scaling relationships, vitally influence the functional viability of machines intended for industrial service. The rotary machine presented in this disclosure illustrates primary geometric relationships and other technical features as developed to resolve viability issues discussed in prior paragraphs. The disclosure provides a technological foundation for creation of industrial-scale rotary vane gas/vapor compressors offering measures of functional efficiency and mechanical reliability equal or superior to the performance capabilities of comparable reciprocating compression machines presently available.
This disclosure presents an independent vane type rotary vane machine for compression of gaseous or vaporous fluids at a power level appropriate for industrial scale service. The disclosure illustrates the geometric relationships and technical features necessary to achieve the measures of single stage pressure amplification, mechanical efficiency, and thermal control necessary to satisfy fundamental functional viability considerations.
The machine consists of a stationary containment structure and an internal rotational assembly. The stationary containment structure features a containment cylinder with a circular bore installed with a mechanically secured closure structure at each axial end and with ports for induction and discharge of throughput fluid. Each end closure structure accommodates bearings for support of the internal rotational assembly, a port for movement of internal thermal control media and a port for extraction of liquid condensate. Ports are also provided for supply and discharge of liquid lubricant to rotational bearings and for insertion of finely dispersed liquid lubricant for lubrication of internal interactively dynamic load bearing surfaces.
The internal rotational assembly primarily features a rotational shaft, a rotational armature, radial vanes, and a radial vane constraint assembly. The rotational shaft axially extends through the containment structure to mechanically interface with an external power source and its rotational axis is parallel to, but radially displaced from, the axis of the containment cylinder bore. The rotational armature is configured as a hollow structural annulus internally contoured to promote heat transfer to internal thermal control media and installed with an integral structural diaphragm at each axial end. Each structural diaphragm is concentrically secured on the rotational shaft and is penetrated by axially aligned ports to permit axial movement of internal thermal control media and with axially aligned ports to permit discharge of condensate liquid. The rotational armature accommodates a radial vane slot at each of twelve centers uniformly spaced around its circumference. Each radial vane slot extends through the radial thickness of the annulus to preclude the requirement for base venting and a linear bearing insert constructed from low-friction bearing material is installed on each side of the radial vane slot. Each pair of linear bearing inserts constrain one radial vane but permit the radial vane radial to slide freely on a radial plane and resiliently accommodate functionally induced deformation of the radial vane and the rotational armature. Each radial vane is proportioned to radially protrude a small distance within the annulus cavity to facilitate heat transfer from the radial vane to internal thermal control media and is installed with a bearing block at each radially outermost axial end. A freely rotating radial vane constraint assembly installed at each axial end of the rotational armature constrains the radial vane bearing blocks and their associated radial vanes against the centripetal force induced by rotational motion. Each radial vane constraint assembly is installed on low-friction rotational bearings to substantially preclude mechanical friction at the interfaces between major rotational components and stationary containment structure. Each radial vane constraint assembly includes an axial seal ring component constructed from graphite, high-temperature ceramic or similar low-friction and wear resistant bearing material. Each axial seal ring is proportioned to concurrently close all radial vane slots at one axial end. Each radial vane constraint assembly includes an axial compression spring that constrains the axial seal ring to maintain pressurized contact with one axial end of the rotational armature and one axial end of all radial vanes and resiliently accommodate function induced axial deformations in these components. Each radial vane constraint assembly is configured to maintain a distance of separation between the outermost radial edge of each radial vane and the containment cylinder bore and relatively lightweight vane edge seal is installed on the each radial vane to bridge the distance of separation. The vane edge seal is radially constrained by its associated radial vane and constructed from spring quality steel or similar resilient material. The vane edge seal is bifurcated along its radially outermost axial edge with the bifurcation edges proportioned to resiliently accommodate function induced diametrical deformation of its interfacing components.
Machine geometry inherently causes relative motions at dynamically interactive sliding interfaces to be sufficiently constrained that, for many applications, these interfaces may be derived to feature self-lubricating materials to minimize the risk of contamination of throughput fluid. However, for many applications, lubrication of internal sliding surfaces by liquid lubricant may be the preferred option and, for this reason, is included in this disclosure.
For purpose of presentation the device is illustrated with ancillary components as appropriate for induction and compression of atmospheric air. Adjustment of external ancillary components may be accomplished for the machine to be compatible with other gaseous fluids, gaseous fluid sources, or for the machine to function as a high vacuum pump. Also for purpose presentation the containment cylinder is illustrated with an arrangement of external ancillary fins for external thermal control and internal thermal control is accomplished by expansion of a portion of compressed throughput fluid. However, the use of liquid for external thermal control and the use of other media for internal thermal control are deemed equally acceptable and may be preferable choices in certain applications. Adjustments of external ancillary components are considered to be within the scope of the invention